The authors report on 14 cases of fulminant and delayed forms of endophthalmitis, in which a diagnostic and therapeutic vitrectomy, were performed. By diagnostic processing of the excised vitreous the chances of obtaining positive findings were increased, especially with a combination of bacteriological and histopathological methods. As advantages of a diagnostic and therapeutic vitrectomy versus purely antibiotic treatment in endophthalmitis the authors discuss the following factors: (1) improved diagnostic possibilities in combination with vitrectomy; (2) a reduction in the quantities of infective organisms and toxins; and (3) improved penetration of antibiotic into and out of the vitreous body cavity.